Forage harvester adjustment apparatus

ABSTRACT

An adjustment apparatus for a forage harvester including a shear bar which is adjustably mounted on a housing which supports a chopper drum mounted for rotation about an axis and having a plurality of circumferentially spaced knife supports holding adjustably secured chopper knifes. The chopper knives act with the shear bar to chop incoming crop. The adjustment apparatus includes a lateral element, at least one location element and at least one radially inwardly directed guide surface, which follows a desired outer path of an unworn chopper knife.

FIELD

The present disclosure relates to an adjustment apparatus for a forageharvester and in particular to an adjustment apparatus for adjustment ofthe chopper knives on a chopper drum.

BACKGROUND

The adjustment apparatus is suitable for use with an agriculturalharvesting machine, in particular, a forage harvester, provided with achopper drum assembly comprising a rotatable chopper drum having aplurality of knives. In use the chopper drum rotates opposite astationary shear bar. There is a gap between the shear bar and theplurality of knives into which crop is fed during harvesting, the fedcrop is chopped between the knives and the shear bar. Such harvestingmachines require regular maintenance of the chopper drum assembly andthe shear bar in order to maintain the quality of the chopping process.

The chopping of incoming crop causes wear on the knives and on the shearbar of the chopper drum assembly. This action may also cause the shearbar to become incorrectly adjusted. If chopping is performed using bluntknives and/or with a shear bar that is incorrectly adjusted this leadsto a reduction in the chopping quality and increased energy consumptionin driving of the chopper drum assembly.

It is therefore necessary at periodic intervals to perform maintenanceactions on the chopper drum assembly for example to replace blunt knivesand/or to adjust the shear bar in order to obtain a suitable cuttinggap. During such maintenance it is important to ensure the replacementknives are located in the correct positions. Aligning and fixing inplace the replacement knives can be a time consuming operation.

The present embodiment addresses the above problems. Other advantageswill become clear from the following description.

BRIEF SUMMARY

According to a first embodiment of an adjustment apparatus for use witha forage harvester, a shear bar is adjustably mounted on a housing, achopper drum is supported from the housing and mounted for rotationabout a rotational axis and further provided with a plurality ofcircumferentially spaced knife supports to which at least one chopperknife can be adjustably secured and wherein in use the chopper knivescooperate with the shear bar to chop incoming crop, the adjustmentapparatus comprises a lateral element, at least one location element forlocation of the adjustment apparatus with respect to the chopper drumand at least one radially inwardly directed guide surface, the or eachradially inwardly directed guide surface describing an outer path of anunworn chopper knife.

This has as an advantage that the adjustment apparatus allows theaccurate concentric adjustment of the chopping knives.

In one embodiment, the at least one location element comprises alocating surface for mating or engagement with a receiving surface ofthe forage harvester.

In one embodiment, the or each guide surface comprises one or morespacer elements, the or each spacer element being connected to thelateral element.

In one embodiment, the or each radially inwardly directed guide surfaceis adjustably located with respect to the lateral element.

In one embodiment, the adjustment apparatus further comprises at leastone shear bar alignment surface provided on one or more of the at leastone location elements. An additional shear bar surface may also beprovided on one or more spacer elements, the or each spacer elementbeing connected to the lateral element.

Alternatively, the adjustment apparatus further comprises at least oneshear bar alignment surface provided on one or more of the at least onelocation elements. In one embodiment, an additional shear bar surface isprovided on one or more of the spacer elements.

In one embodiment, lower surfaces of the one or more spacer elementsserve as the or each additional shear bar alignment surface.

This has as an advantage that it allows the accurate adjustment of theshear bar relative to the chopping drum, since in use once theadjustment apparatus has been secured in position, the shear bar may beadjusted such that an upper surface of the shear bar can be brought intoa mating arrangement with the shear bar alignment surface(s) and securedinto the correct position.

This also has as an advantage that it allows the accurate adjustment ofthe chopping knives relative to a correctly positioned shear bar, sinceonce the shear bar has been adjusted the guide surfaces will becorrectly located for positioning of the edges of the adjustable chopperknives with respect to the desired outer path of an unworn chopperknife.

Alternatively, the adjustment apparatus may provide a second lateralelement spaced from the first. In this embodiment, the or each spacerelement extends between the first lateral element and the second lateralelement.

In one embodiment, the or each location element extends between thefirst lateral element and the second lateral element.

In one embodiment, the adjustment apparatus further includesmanipulation means.

According to a second embodiment, a system comprises a forage harvesterand an adjustment apparatus according to the first embodiment in whichthe forage harvester comprises a shear bar adjustably mounted on ahousing, a chopper drum supported from the housing and mounted forrotation about a rotational axis and further provided with a pluralityof circumferentially spaced knife supports to which at least one chopperknife can be adjustably secured.

In one embodiment, engagement means engage the at least one locationelement with the forage harvester.

In one embodiment, the or each radially inwardly directed guide surfaceextends about circumferentially adjacent chopper knives of the chopperdrum.

According to a third embodiment, a method of adjustment of at least onechopper knife of a chopper drum in a forage harvester using anadjustment apparatus in accordance with the first embodiment comprisesthe steps of: locating the at least one locating surface with respect toa receiving surface of a chopper drum housing or a receiving surface ofa chopper drum, aligning the at least one locating surface with a sideof the chopper drum housing to allow engagement of the engagement meansto secure the adjustment apparatus in relation to the chopper drumhousing, inspecting the one or more chopper knives on the chopper drumadjacent to the adjustment apparatus and adjusting or replacing thechopper knives as required, rotating the chopper drum as necessary tobring a new chopper knife or set of chopper knives adjacent to theadjustment apparatus, once all of the chopper knives have been inspectedand the necessary action taken, releasing the engagement means andremoving the adjustment apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments will now be described, by way of example only, withreference to the accompanying drawings, in which:

FIG. 1 shows a schematic side view of a forage harvester for use withthe disclosed embodiments;

FIG. 2 shows a perspective view of a chopper drum and housing to whichan adjustment apparatus in accordance with a first embodiment has beensecured;

FIG. 3 shows a perspective view of the chopper drum and the adjustmentapparatus of FIG. 2;

FIG. 4 shows a detail of the chopper drum and the adjustment apparatusof FIG. 2;

FIG. 5 shows a perspective view of the adjustment apparatus of FIG. 2;

FIG. 6 shows a first sectional view of the chopper drum and theadjustment apparatus of FIG. 2;

FIG. 7 shows a second sectional view of the chopper drum and theadjustment apparatus of FIG. 2;

FIG. 8 shows a perspective view of a chopper drum and housing to whichan adjustment apparatus in accordance with a second embodiment has beensecured;

FIG. 9 shows a perspective view of the chopper drum and the adjustmentapparatus of FIG. 8;

FIG. 10 shows a detail of the chopper drum and the adjustment apparatusof FIG. 8;

FIG. 11 shows a perspective view of the adjustment apparatus of FIG. 8;

FIG. 12 shows a first sectional view of the chopper drum and theadjustment apparatus of FIG. 8;

FIG. 13 shows a second sectional view of the chopper drum and theadjustment apparatus of FIG. 8;

FIG. 14 shows a perspective view of a chopper drum and housing to whichan adjustment apparatus in accordance with a third embodiment of thepresent invention has been secured;

FIG. 15 shows a perspective view of the chopper drum and the adjustmentapparatus of FIG. 14;

FIG. 16 shows a detail of the chopper drum and the adjustment apparatusof FIG. 14;

FIG. 17 shows a perspective view of the adjustment apparatus of FIG. 14;

FIG. 18 shows a first sectional view of the chopper drum and theadjustment apparatus of FIG. 14;

FIG. 19 shows a second sectional view of the chopper drum and theadjustment apparatus of FIG. 14; and

FIG. 20 shows a side section though a fourth embodiment of the presentinvention illustrating a method of calibration.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

The embodiments will now be described in the following detaileddescription with reference to the drawings, wherein certain embodimentsare described in detail to enable practice the embodiments disclosedherein. Although the details are described with reference to specificembodiments, it will be understood that the disclosure is not limited tothese embodiments. But to the contrary, the disclosure includes numerousalternatives, modifications and equivalents as will become apparent fromconsideration of the following detailed description.

Reference to terms such as longitudinal, transverse and vertical aremade with respect to a longitudinal vehicle axis which is parallel to anormal forward direction of travel.

With reference to FIG. 1, in a schematic side view the main componentsof a forage harvester 2 are shown. The forage harvester 2 is providedwith a front attachment 4 which contains cutting equipment for cutting acrop. The cut crop is then fed through a series of compression rollers 6in a compression roller housing 8 to a chopper drum 10 where the crop ischopped into smaller pieces between a shear bar and a plurality ofchopper knives mounted on the chopper drum 10. The chopped crop nextpasses through a first duct 12 and, in the illustrated embodiment, isfed through a cracker unit 14 where the crop is further crushed andthreshed. The harvested crop is then blown upwards along a second duct16 by an accelerator 18 and exits through a spout 20. In an alternativeembodiment, the chopped crop may optionally pass directly from thechopper drum to the first duct.

As noted, overtime chopping of the incoming crop causes wear on thechopper knives and on the shear bar, and can cause the shear bar tobecome incorrectly adjusted. While it is known to provide a knifesharpening apparatus within such forage harvesters, which is operatedfrom time to time to maintain the sharpness of the cutting knives, itremains the case that after repeated sharpening, the cutting knives wearaway and the cutting knifes need to be replaced.

It is therefore necessary over time as part of the ongoing maintenanceof the chopper drum to perform a number of tasks including i) replacingworn, blunt knives with new knives in a suitable position to ensurecorrect interaction in use with the shear bar; ii) where knifes may beadjusted rather than replaced, adjusting the position of the knivesrelative to the shear bar to ensure correct interaction between eachknife and the shear bar; and iii) precisely adjusting a location of theshear bar in order to obtain or maintain a suitable cutting gap.

In short, during such maintenance it is important to ensure the (worn orreplacement) knives are located in the correct position in relation to acorrectly adjusted shear bar to result in proper operation of thechopping drum—both for chopping of crop and to guarantee that the knivesare in the correct position to be sharpened by the knife sharpeningapparatus.

The present disclosure relates to an adjustment apparatus for use duringsuch maintenance. In describing the adjustment apparatus the term‘inner’ is used to describe that portion of the adjustment apparatuswhich is, in use, oriented toward the chopper drum and ‘outer’ theopposite. Similarly references to ‘upper’ and ‘lower’ are to beunderstood with the adjustment apparatus in this position.

FIGS. 2 to 7 illustrate an adjustment apparatus 50 according to a firstembodiment of the present invention.

FIG. 2 shows a frame 22 in which a chopper drum 10 is mounted. An upperend of the frame 22 is provided with a housing 24 within which asharpening apparatus (not shown) may be located. The frame 22 isprovided with first and second parallel side walls 26,28. A lower end ofeach side wall 26,28 is provided with a mounting means to support ashear bar 30 in an adjustable manner.

A chopper drum assembly is mounted in central portion of the frame 22supported between the side walls 26,28.

The frame 22 is further provided with further mounting means to enablethe frame 22 to be located in a suitable position within the forageharvester. Each side wall 26,28 is further provided with a mountingopening 36 as described below.

The chopper drum assembly is shown in more detail in FIG. 3 and FIG. 4.

The chopper drum assembly comprises a chopper drum 10 supported forrotation about a longitudinal axis on a drive shaft 42. The chopper drum10 is further provided with a plurality of chopper knives 46 mountedabout a peripheral circumferential surface of the chopper drum 10. Theknives 46 may be mounted to the chopper drum 10 in any suitable manner.Conveniently, a first set of knives extends across a first half of thedrum (from a first end to a mid-point) and a second set of knivesextends across a second half of the drum (from the mid-point to a secondend)

The adjustment apparatus 50 according to the first embodiment comprisesa lateral element 52. In the illustrated embodiment the lateral element52 is of substantially L-shaped section. The lateral element 52 issecured between first and second location elements 54,56.

Each location element 54,56 corresponds to the other and only one willbe described here. Each end of the lateral element 52 is fixedly securedin any suitable manner to the location element 54,56. In the illustratedembodiment (cf FIGS. 5 and 6) tabs projecting from the ends of thelateral element 52 are received in corresponding openings (slots orrecesses) of the respective location elements 54,56. An opposite end isprovided with a locating surface 58. At least one opening 60 for afastening is provided between the ends of the location element 56. Alower surface of each location element 56 is provided with a shoulder 62beneath the region of the lateral element 52 in use secured to thelocation element 56. Each shoulder 62 comprises an elongate portion 64and shorter portion 66.

The adjustment apparatus 50 further comprises a plurality of spacerelements 70. In the embodiment illustrated, three such spacer elements70 are shown. One spacer element 70 is located centrally and the othertwo spacer elements 70 are each located adjacent a respective locationelement 54,56.

Each spacer element 70 is fixedly secured to the L-shaped lateralelement 52. Each spacer element 70 is generally L-shaped having agenerally horizontal portion 72 connected to a generally dependingportion 74. A lower surface 76 of the generally horizontal portion 72extends across an upper surface 78 of the lateral element 52 (cf FIG.7). An outer surface 80 of the generally depending portion 74 extendsalong an inner vertical surface 82 of the lateral element 52. A lowerpart of the generally depending portion 74 conveniently comprises ashoulder portion 84 such that in use the vertical portion of the lateralelement 52 is seated between the shoulder portion 84 and the lowersurface 76 of the generally horizontal portion 72. (cf FIG. 7).

A lower surface 86 of the depending portion 74 of the spacer element 70is preferably aligned with the elongate portions 64 of the shoulder 62of the location elements 54,56. A guide surface 88 of the dependingportion 74 of each spacer element 70 is shaped to describe the desiredpath of an unworn chopper knife (cf dotted line in FIG. 7).

The upper surface 78 of the lateral element 52 is conveniently providedwith manipulation means 90 in the form of two spaced handles. Each ofthe handles is located between a respective set of spacer elements 70.

In use the adjustment apparatus 50 is manoeuvred generally into positionusing the manipulation means 90. Each of the locating surfaces 58 isplaced against a suitable surface on the chopper drum assembly, forexample a surface of the drive shaft 42.

In an alternative embodiment (not shown) the lateral elements areconfigured such that each of the locating surfaces instead may be placedagainst other surfaces of the chopper drum assembly such as the ringflanges securing the chopper drum to the drive shaft 42 or shaftbearings provided on the drive shaft.

In a still further alternative embodiment (not shown) the lateralelements are configured such that each of the locating surfaces isplaced against a suitable surface of the frame in which the chopper drumis mounted.

It will be understood that given the need for correct alignment of thechopper knives in use, the arcuate inner surfaces 88 of each the spacerelements 70 are arranged to be concentric with the rotational axis ofthe drive shaft 42.

The adjustment apparatus 50 is then adjusted such that the openings 60in each of the location elements 54,56 align with the mounting openings36 in the respective side walls 26,28 of the frame 22. Suitablefasteners 92 are passed through the aligned openings 36,60 (for examplethreaded fasteners are secured in threaded bores) to locate and fix theadjustment apparatus 50 with respect to the frame 22 (and so therotational axis of the drive shaft 42 of the chopper drum 10).

Once the adjustment apparatus 50 is in the desired position the shearbar 30 may be released and adjusted as necessary and then secured intothe correct position. As shown in FIG. 6, a sectional view taken throughone of the location elements 54,56, the elongate portion 64 of theshoulder 62 of each location element 54,56 serves to provide a firstshear bar adjustment surface by which an upper surface 94 of the shearbar 30 may be located and the shorter portion 66 of each shoulder 62serves to provide a second shear bar adjustment surface by which a sidesurface of the shear bar 30 adjacent the chopper drum 10 may be located.

FIG. 7 shows a section in line with one of the spacer elements.

Where the lower surface 86 of the middle spacer element is aligned withthe elongate portion 64, since the ends of the shear bar 30 arecorrectly located with respect to the chopper drum 10, a user canswiftly, as a result of visual inspection, determine if the shear bar 30is correctly aligned at the midpoint, that is that the upper surface 94of the shear bar 30 mates with the lower surface 86 of the middle spacerelement 70 (that is the shear bar alignment surface formed by the lowersurface 86). If it does not, for example because the shear bar 30 hasbecome damaged or unevenly worn, the user can replace the shear bar 30as required.

In addition, the position of the chopper knives 46 with respect to theshear bar 30 may be adjusted by adjusting the edges of the choppersknives 46 to bring the edges into contact with the arcuate surface ofthe inner surface 88 of the depending portions of the spacer elements70. Once each chopper knife 46 has been adjusted the chopper drum 10 isrotated to bring the next chopper knife 46 into proximity with theadjustment apparatus 50.

FIGS. 8 to 13 illustrate a second embodiment of an adjustment apparatus150 according to the present disclosure. The chopper drum assembly ofFIGS. 8 to 13 corresponds to the chopper drum assembly of FIGS. 2 to 7and like reference numerals are used to refer to like parts. Similarly,to the extent that elements of the second embodiment of the adjustmentapparatus correspond to similar elements of the first embodiment of theadjustment apparatus, similar reference numerals are used.

The adjustment apparatus according to the second embodiment comprises afirst lateral element 152. In the illustrated embodiment the firstlateral element 152 comprises a bar having a flat lower surface. Thefirst lateral element 152 is secured between first and second locationelements 154,156.

Each location element 154,156 corresponds to the other and only one willbe described here. Each location element 156 is generally arcuate andcomprises a first radial member 198 and a second radial member 200. Eachradial member is provided with at least one opening 160 for a fastening.An inner end of each radial member 198,200 is joined by an inner arcuatemember 202. An inner surface of the inner arcuate member 202 is formedas a locating surface 158. An outer end of each radial member 198,200 isjoined by an outer arcuate member 204. The outer end of each firstradial member 198 is provided with a shoulder 162. The shoulder 162 isprovided with an elongate part 164 and a shorter part 166. The elongate164 part is provided with a cut away portion 168 in which an end of thefirst lateral element 152 may be located and secured. The outer end ofeach second radial member 200 is provided with a cut away portion 268 inwhich an end of a second lateral element 252 may be located and secured.Each location element 154,156 may be formed in any suitable manner, forexample as a unitary part as in the illustrated embodiment. Each lateralelement 152,252 may be secured in relation to each location element154,156 in any suitable manner.

The adjustment apparatus 152 further comprises a plurality of spacerelements 170. Each of the spacer elements 170 extends between the firstlateral element 152 and the second lateral element 252. Each spacerelement 170 is provided at each end with a cut away portion 148,248 toreceive one of the lateral elements 152,252. An arcuate surface 188 ofeach spacer element 170 is shaped to describe the desired path of anunworn chopper knife (as shown by the dotted line in FIG. 13).

In the embodiment illustrated four such spacer elements 170 are shown.Two of the spacer elements 170 are located adjacent a respectivelocation element 154,156. The other two spacer elements 170 are locatedto either side of a central region of the adjustment apparatus 150. FromFIGS. 8 to 10 it can be seen that two of the spacer elements 170 to oneside of the adjustment apparatus 150 are generally aligned with thechopper knives 46 on one side of the chopper drum 10 and the other twoof the spacer elements 170 to the other side of the adjustment apparatus150 are generally aligned with the chopper knives 46 on the other sideof the chopper drum 10.

In use the adjustment apparatus is manoeuvred generally into position.Each of the locating surfaces 158 is placed against a suitable surfaceon the chopper drum assembly, for example a surface of the drive shaft42 (cf FIG. 12).

In an alternative embodiment (not shown) the lateral elements areconfigured such that each of the locating surfaces instead may be placedagainst other surfaces of the chopper drum assembly such as the ringflanges securing the chopper drum to the drive shaft 42 or shaftbearings provided on the drive shaft.

In a still further alternative embodiment (not shown) the lateralelements are configured such that each of the locating surfaces isplaced against a suitable surface of the frame in which the chopper drumis mounted.

Given that, as noted above, the arcuate surface 188 of each spacerelement 170 is shaped to describe the desired rotational path of anunworn chopper knife it will be understood that in order to correctlyalign the chopper knives, the arcuate surfaces 188 of each the spacerelements 170 are arranged to be concentric with the rotational axis ofthe drive shaft 42.

The adjustment apparatus 150 is then adjusted, as necessary, such thatthe openings 160 in the radial members 198,200 of the location elements154,156 align with corresponding openings 36 in the respective sidewalls 26,28 of the frame 22. Suitable fasteners 192,292 are passedthrough the aligned openings 136,160 to locate the adjustment apparatus150 with respect to the frame 22 (and so the rotational axis of thedrive shaft 42 of the chopper drum 10).

Once the adjustment apparatus 150 is in position the shear bar 30 may bereleased and adjusted as necessary and then secured into the correctposition. As shown in FIG. 12, a sectional view taken through one of thelocation elements 154,156, the elongate portion 164 of the shoulder 166of each location element 154,156 serves to provide a first shear baradjustment surface by which an upper surface 94 of the shear bar 30 maybe located.

FIG. 13 shows a section in line with one of the spacer elements 170.Since the ends of the shear bar 30 are correctly located with respect tothe chopper drum 10, and the lower ends of the spacer elements (and inparticular the lower surface of the first lateral element 152 and lowerend 196 of the spacer elements 170 are aligned with the elongate portion164 of the shoulder 166 of each location element 154,156), a user canswiftly, as a result of visual inspection, determine if the shear bar 30is correctly aligned across the working width of the shear bar 30, thatis that the shear bar 30 mates with a lower surface defined by the lowerend 196 of the spacer element 170 and the lower surface of the firstlateral element 152 (that is the shear bar alignment surface). If itdoes not, for example because the shear bar 30 has become damaged orunevenly worn, the user can replace the shear bar 30 as required.

Also the position of the position of the chopper knives 46 with respectto the shear bar 30 may be adjusted by adjusting the edges of thechoppers knives 46 adjacent to the spacer elements 170 to bring theminto contact with the arcuate surfaces 188 of the spacer elements 170.It may be seen that, in comparison with the first embodiment, the longerarcuate surfaces 188 of the spacer elements 170 of the second embodimentenable adjustment of more chopper knives 46 for a particular rotationalposition of the chopper drum 10. Once each set of chopper knives 46 hasbeen adjusted the chopper drum 10 is rotated to bring the next set ofchopper blades 46 into proximity with the adjustment apparatus 150.

FIGS. 14 to 19 illustrate a third embodiment of an adjustment apparatus250 according to the present disclosure. The chopper drum assembly ofFIGS. 14 to 19 corresponds to the chopper drum assemblies of FIGS. 2 to7 and FIGS. 8 to 13 and like reference numerals are used to refer tolike parts. Similarly, to the extent that elements of the thirdembodiment of the adjustment apparatus correspond to similar elements ofthe first and second embodiments of the adjustment apparatus, similarreference numerals are used.

It can be seen that the third embodiment is most similar to the firstembodiment, with the principal difference being the elongate nature ofthe spacer elements 370 and, in particular, it can be seen that theinner surface 388 of each spacer element 370 extends from a lower pointadjacent the generally depending portion of the lateral element 352 (incommon with the first embodiment) and extends substantially upwards. Inpractice it is preferred that that the inner surface 388 of each spacerelement 370 extends such that two circumferentially adjacent chopperknifes 46 of the chopper drum assembly are covered (in common with thesecond embodiment).

It will be understood that the advantages of the first and secondembodiments also follow from this construction.

The adjustment apparatus may be manufactured in any suitable manner. Forexample the various elements may be first welded together and then theinner surfaces of the spacer elements and the appropriate shear baradjustment surfaces milled or otherwise machined to the desired shapesand tolerances.

A fourth embodiment of the disclosure is shown in FIG. 20. Thisembodiment is substantially similar to the first embodiment, and to theextent that elements of the fourth embodiment of the adjustmentapparatus correspond to similar elements of the previous embodiments ofthe adjustment apparatus, similar reference numerals are used.

In this embodiment, the spacers 470 are adjustable with respect to thelateral element 452. In the illustrated embodiment, the lateral element452 is secured in a fixed position between first and second locationelements 456 (only one is seen in the view of FIG. 20). However thelimbs of the lateral element 452 are provided with first and secondopenings 479,483 through which the spacer elements 470 may be secured tothe lateral element 452. The spacer elements 470 are further providedwith first and second openings 473, 475 through which the spacerelements 470 and the lateral element 452 can be secured together. Thelateral element 452 is additionally provided with at least one furtheropening 481 through which the position of each of the spacer elements470 can be set with respect to the lateral element 452.

The first opening 479 is provided in a substantially horizontal limb ofthe lateral element and adapted to align with the first opening 473 inthe substantially horizontal portion 472 of the spacer element 470. Theopening in the substantially horizontal portion 472 of the spacerelement 470 comprises a threaded bore adapted to receive a suitablethreaded fastener 485, such as a headed bolt. The first opening 479 inthe substantially horizontal limb of the lateral element 452 is sized toallow a shaft of the threaded fastener 485 freely to pass through.

The second opening 475 is provided by a threaded bore in a dependingportion 474 of the spacer element 470. The second opening 483 in thelateral element 452 is provided as a substantially vertically disposedslot. The slot is aligned with the threaded second opening 475 in thedepending portion 474 of the spacer element 470. A threaded headedfastener 487 passes through the slot into the threaded bore. It will beunderstood that in this way the spacer 470 may be adjusted substantiallyvertically with respect to the lateral element 452 in a manner to bedescribed.

The further opening 481 in the substantially horizontal limb of thelateral element is a threaded bore adapted to receive a threaded headedfastener 489.

The lateral element 452 and the location elements are assembled togetherin any suitable manner. The spacer units 470 are then located in anapproximate position with respect to the lateral element 452 of theadjustment apparatus. It will be understood that the horizontalrelationship can be set by inserting the threaded headed fastener 487thorough the opening 483 and into the bore 475 and tightening thethreaded headed fastener 487 to draw the spacer against the dependingportion 474 of the spacer element 470. The second fastener 485 can beused to roughly locate the substantially horizontal portion 472 of thespacer element 470 with respect to the lateral element 452. The thirdthreaded fastener 489 can be located in the further opening 481 of thelateral element 452.

The adjustment assembly is then placed in position against a chopperdrum assembly that does not require adjustment (or a corresponding rigset up to replicate such an assembly). By adjustment of the second andthird threaded members 485,489 the vertical positioning of the spacerelement 470 with respect to the lateral element 452 can be adjusted, forexample in FIG. 20 by movement from the position shown in unbroken linesto the position shown in dashed lines.

Once the adjustment apparatus has been correctly calibrated, it can beremoved from the chopper drum (or calibration rig) for use in adjustingworn or incorrectly positioned chopper blades.

From reading the present disclosure, other modifications will beapparent to persons skilled in the art. Such modifications may involveother features which are already known in the field of forage harvestersand component parts therefore and which may be used instead of or inaddition to features already described herein.

1. An adjustment apparatus for use with a forage harvester, in which ashear bar is adjustably mounted on a housing, a chopper drum issupported by the housing and mounted for rotation about a rotationalaxis and comprises a plurality of circumferentially spaced knifesupports for adjustably securing at least one chopper knife, wherein thechopper knives cooperate with the shear bar to chop incoming crop, theadjustment apparatus comprising: a lateral element, at least onelocation element for location of the adjustment apparatus with respectto the chopper drum; and at least one radially inwardly directed guidesurface, wherein each of the guide surfaces is configured to align withan outer path of an unworn chopper knife.
 2. The adjustment apparatus ofclaim 1, wherein the location elements comprise a locating surface forengagement with a receiving surface of the forage harvester.
 3. Theadjustment apparatus of claim 1, wherein the guide surfaces are on oneor more spacer elements, wherein the spacer elements are connected tothe lateral element.
 4. The adjustment apparatus of claim 1, wherein theguide surfaces are adjustably located with respect to the lateralelement.
 5. The adjustment apparatus of claim 1, further comprising atleast one shear bar alignment surface on at least one of the locationelements.
 6. The adjustment apparatus of claim 5, comprising anadditional shear bar alignment surface on at least one spacer element,wherein the spacer elements are connected to the lateral element.
 7. Theadjustment apparatus of claim 3, wherein the adjustment apparatusfurther comprises at least one shear bar alignment surface on at leastone of the location elements.
 8. The adjustment apparatus of claim 7,comprising an additional shear bar alignment surface on at least one ofthe spacer elements.
 9. The adjustment apparatus of claim 6, wherein alower surface of at least one spacer element is the shear bar alignmentsurface.
 10. The adjustment apparatus of claim 1, further comprising anadditional lateral element spaced from the lateral element.
 11. Theadjustment apparatus of claim 10, wherein spacer elements extend betweenthe lateral element and the additional lateral element.
 12. Theadjustment apparatus of claim 11, wherein the location elements extendbetween the lateral element and the additional lateral element.
 13. Theadjustment apparatus of claim 1, further comprising manipulation means.14. A system for adjusting crop chopping equipment: a forage harvester;and an adjustment apparatus comprising: a shear bar adjustably mountedon a housing; a chopper drum supported from the housing and mounted forrotation about a rotational axis comprising a plurality ofcircumferentially spaced knife supports for adjustably securing at leastone chopper knife wherein the chopper knives cooperate with the shearbar to chop incoming crop; a lateral element; at least one locationelement for location of the adjustment apparatus with respect to thechopper drum; and at least one radially inwardly directed guide surface,wherein each of the guide surfaces is configured to align with an outerpath of an unworn chopper knife.
 15. The system of claim 14, wherein atleast one location element is engaged with the forage harvester.
 16. Thesystem of claim 14, wherein the radially inwardly directed guidesurfaces extend between at least two circumferentially adjacent chopperknives of the chopper drum.
 17. A method of adjusting chopper knifes ofa chopper drum in a forage harvester using an adjustment apparatuscomprising: locating at least one locating surface of the adjustmentapparatus with respect to a receiving surface of a chopper drum housing;aligning the locating surface with the receiving surface of the chopperdrum housing; securing the locating surface to the receiving surface;inspecting the chopper knives on the chopper drum adjacent to theadjustment apparatus; adjusting or replacing the chopper knives asnecessary; rotating the chopper drum; inspecting and adjusting orreplacing the chopper knives adjacent to the adjustment apparatus;continuing to rotate, inspect and adjust or replace the chopper knivesadjacent to the adjustment apparatus until all of the chopper kniveshave been inspected and adjusted or replaced as necessary; and releasingthe adjustment apparatus from the chopper drum housing.
 18. Theadjustment apparatus of claim 7, wherein a lower surface of at least oneof the spacer elements is the shear bar alignment surface.